VU Field course hydrology, Aveiro 2011

Saturday, June 25, 2011

This probably will be the last post for this field course, from out of the field that is. The students are at home and Michel and I are on our way back, staying in hot hotel rooms after a simmering drive to the North of Spain in our blue jam jar. I am feeling like a fat dog after today.

I am dedicating this post to all of our students, and in particular to Anna, who may have to explain some of the finesses of the English language in this gibberish post to her fellow students. With this field course done, they must be considered young humdingers of hydrologists.

The famous welcome sign to the field course area

I would also like to thank all the Portuguese people for their hospitality and giving us who gave us access to their land. In particular, I would like to thank the Caromario family who threw us a party in Montouro that we'll never forget. A picture of the delicious leitao offered to us already appeared in a previous post, but here it is again with people eating it. Mario, Carolina, muito obrigado para este festa com vinho, batates fritas e leitao!

Leitao party in Montouro with Mario's family and friends.

But let's not dwell on this too much, I do not want to get the mulligrubs, but go back to the balmy days in our the fields around the peaceful dwelling of Montouro, where we did a spiffy pumping test, VESses, and a lot of other things, all in a jiffy. Of course the men's team also went to the Sao Joao party in Porto, without any shot clogs that is.

The pumping test was a first in this field course in Portugal and was made by six of our students (Rosa, Nadine, Sonia, Inge, Anna and Corine) within the smelly bounds of their garbage dump, which should be the perfect place for lingering bowerbirds.

Apparantly the test was initiated because they got tired of doing these small-scale ring infiltrometer tests. This is particularly true for Anna, who was was voted to be this years "Queen of the Rings"...

So for all of you twacks who aren't versed in hydrology and read this blog, a pumping test can be described as pumping groundwater from a perforated tube in the soil and measuring the change of the waterlevel in an adjacent tube that "sees" the drawdown caused by the removal of groundwater by the pump. This is usually done for fun by hydrologists to get out of their dull offices, but it also gives us some kind of estimate of the permeability of the soil for water flow.

Excitement surrounding this mystical pumping test event. While Corine, Anna and Nadine are staring into a hole in the ground where mysterious flows of waters occur due to the action of our small pump, Rosa claps her hands in excitement as water is indeed entering the grey box and Sonia does a small dance also known as El Mapalé. Michel, the crambazzled looking guy, is leading the whole effort.

On the same day, they also manage to install a minifilter piezometer to analyse chemical profiles of the groundwater.

Proud owners of the first student-made minifilter piezometer

So this was a great succes that had to be conquered by the thrillseeking "com uma rocketa" Hanson quartet. They decided to do their last Vertical Electrical Sounding, better known by the boys as their final VES.

Last VES of the boyz

The idea was that they would find a shallow ridge of clay under their sandy catchment by looking at the resistivity values produced by their ruthless application of 400 volts to the soil. One of the Rugo twins decided that this was best done barefoot, not realising that their loyal partner Sjef could, by erroneously pressing a red button on the Terrameter, apply 400 volts to an electrode held by the barefoot wassack. To up it all, they had to use the booster enhancing the voltage to 800 volts. Such a mistake made by Sjef would have given a whole new meaning to the bad hair day look for one of these guys. This all happened next to a deep dug well, of which the kind but flabbergasted owner already had explained to them that there was no Argila to be found beneath his well. But after this action all remains hunky dory with our blokes.

In the meantime, the Lieke, Carolina and Nikki (LCN) group managed not to get lost in a corn field while exploring a nifty deep well with nitrate-rich water. They also did manage to make a piezometer in their geologically complex area to make the first measurements of the water level in this formation and developed several daunting ideas to explain their geology.

The corn experience...

On the last days of our studies, everybody had to measure the change in storage in soil moisture and groundwater, which is often done in large dug wells (called Poços or Noras). The picture below shows an oversized well being measured by LCN, again uder the watching eye of Michel.

Measuring a Poço in low permeability soil

Now comes the hard part, that is writing up scientific reports of their findings. We'll keep you updated!!!

Monday, June 13, 2011

Lake Pateira has at least one similarity with Loch Ness: its "great fault" (the Great Glenn fault in Loch Ness devides Scotland from England). We wanted to prove this with geophysics, measuring the resistivity of the sub surface until a depth of 60 meters. Different layers have different resistivities, when there is a discontinuity you can see this in the resistivities, at least this was the idea.

To measure the resistivity we had to roll out a cable of 400 mtr at the bottom of the lake from a small boat. The cable has 61 graphite electrodes and once unrolled at the bottom of the lake a dedicated computer measures the resistivity at different electrode combinations. This will result in more than 1000 data points which can be “transformed” to a 2D modelled resistivity picture of the sub surface. The result was clear evidence of an abrupt vertical change in the resistivity in the central part of the lake.

The next step will be to see if we can trace the fault back in other parts of the lake and we also might find evidence of a monster in the lake.....

Saturday, June 11, 2011

The Fieldwork shows real dedication to science! DiscoDisco, discordance, discoballs. The terrameter is rupsig (not possible to translate), guys in the field with the terrameter: Electrify the bitch! At the end of the day Julian has our darling (the terrameter) on his lap. well well watertight!! Nerd on board, como una racketa & the tubo de sol. All the guys in the cellar and in the racemonster. Everybody is driving... Do the stuifzand. Search the piezometer (measuring tube) for 2 hours before fallen over it. Your carefully placed totalizer is ploughed to pieces. Looking for a ppa (Personal Portugese Assistant) and avoiding a pdn (personal digital nightmare). Put the radio on CidadeFM. And in the weekend go to the pleasureparc.All this with tremendous amounts of nutrients!

Tuesday, June 7, 2011

We always start our field course with a select team of students setting up a meteorological tower that will give them potential evaporation, as evaporation is always the largest component in our water balance.

Corine, Sjef, Sonia and Michel working on the meteorology

Ecohydrology is the science of water and ecosystems. Studying this can be done with computer models, which is tedious work, bad for your back and only sometimes useful. The answer on how ecosystems really behave, however, can only be found in the field. The quest here in this field course is to find out how trees behave. This means that we want to find out at what time they wake up in the morning and start consuming water and nutrients, how much water they transpire, and when they go to sleep in the evening.

We have a little trick that allows us to find this out, which is called the sapflow method. Yes, we are measuring sapflow and we do this by sticking needles in the tree, in its sapwood where the water is transported up to the leaves. This means that we have to drill small holes in the tree to stick the needles in, here gently done by Nikki. One of these needles is heated, while the other one is at normal temperature. The heated needle will lose heat depending on the velocity of the sap in the stem and by comparing this with the non-heated needle we can find out when sapflow occurs and what the velocity is. Then we wrap the stem in aluminum foil and start the power and logging system.

The sapflow team done with their business

The following days were spent on hydrochemistry, taking samples from open wells, rivers, and piezometers. As our piezometers are not installed with the purpose of having access to clean drinking water, we often have a lot of suspended matter in our water and this needs to be filtered out, with force! This is done here by the team of Lieke, Carolina and Nikki, with Carolina turning red from the effort.

Pushing muddy water through a filter

Of course there are easier ways as Anna, Rosa and Sonia are demonstrating in a very nicely restored fonte where the older Portuguese get their lunch water.

Water sampling at Fonte de Angeao

We'll ship these sample to the VU University where they will be analysed and published in the papers written by our students in July. Ate logo!!!

Monday, June 6, 2011

All the instruments are in the field now, at least our Ford van is empty. This year the students seem to have a "tremendous go", no time for coffee, they want to have it all. The only thing that is missing until now is water, the "rios" are at a very low level (tremendously low some would say) and everybody is waiting for the rain to come. We spotted some thunderstorms but they did not provide any rain so far.No worries, dry periods are even more interesting for hydrologists, we like the extremes, we need these in order to predict the effects of climate change.

We already met some of our Portuguese friends, especially Mario and Carolina in Montouro (no centro do mundo). Their bar is the place to be in the centre of this small town and they make us really feel at home (thank you!). This is were we meet the students in the field for instruction and discussions.

Next weekend we will join Carlos Gangreio (University of Aveiro) in his investigations in lake Pateira, we will meassure the earth resistivities down to a depth of 70 meter with an underwater cable of 400 m. When this works, we shall show the results and keep you updated.

Thursday, June 2, 2011

Well, in the previous post we told you something about the excursion. We started our visit with the youngest Cretaceous deposits, which were deposited when dinosaurs roamed the Earth, and then went back in time to the oldest Cretaceous deposits in our area.At the C5 clays we did some geophysics, just to get the hang of it, and because the weather was nice, and to know the resistivity of the clays for later use.After the group picture we went on to these older whitish sands, and we have been staring at these sands for over an hour (see below), which you can only do if you are an earth scientist. So just to baffle all of you non-earth scientists, here are a few professional words that were used many times: crossbedding, muscovite layer, well-rounded poorly sorted, contact spring, aeolian and fluvial deposits, marine clays, pyrite oxidation, conglomerate, discordance and fault. Of course we also found 200 million year old fossils.

The next day we had a day of "learning to know your area" where we pick the right places for installation of rain gauges and discharge measurement stations. With this done, today we went for the real action, which is the installation of stuff and the formal start of our measurement campaign. The staff gauge of the "boy group" was removed by someone very interested in old metal and they had to install a new one. For this activity Sjef had put his yellow underpants and his special boots on, which filled up with water soon after he entered the Sao Romao creek, Julian put on his teletubby suit and Ruben got bitten in his toe by a very aggressive shrimp.